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Basic techniques to repair lenses (and cameras)
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PostPosted: Tue May 21, 2019 1:59 pm    Post subject: Reply with quote

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Last edited by Blazer0ne on Tue Feb 22, 2022 5:22 pm; edited 1 time in total


PostPosted: Wed May 22, 2019 8:29 am    Post subject: Reply with quote

Blazer0ne wrote:
DConvert, Adding my personal garage level experience with over the counter solvents... Hopefully it will compliment your lab experience.

I can confirm that hardware store naptha does soften vinyl work mats and may remove lens element paint. It also evaporates somewhat slower and cuts through oil (tar and grease) nicely.

When cleaning the entire surface of an assembled lens I try to avoid any solvents that evaporate super fast like denatured alcohol or iso-propyl 90%. I only use those solvents when the element is open and separate from the lens housing.

What I have noticed is that the rapid evaporation is causing cooling of the element, which may draw condensation into the backside group or housing.

The most critical personally; Decreased work time because of rapid evaporation may find yourself with no solvent to float the oils while wiping.

Adding a slower evap solvent like Zeiss lens cleaner after applying a rapid evaporating solvent can help with post cleanup of oils without the possibility of ending up with a dry scratchy texwipe, pecpad, cotton swab or kimwipe.

Also note that there is a good chance that many solvents will require the side of an element to be re-painted black.


Like 1 small


Any hydrocarbon solvent will be likely to do all the things you mentioned. Depending on your desired rate of evaporation gasoline, lighter fluid, white spirit, kerosene, or diesel could all be used (listed in decreasing volatility) the last few will leave residues that don't simply evaporate away.
I'm not sure quite what American 'hardware store naptha' is, but I suspect it's a paint thinner/brush cleaner like our white spirit - a turpentine substitute (sometimes sold under that name at higher prices).

Within each of the volatility ranges there will be a wide range of compositions (I've seen hundreds of different gasolines - some very different from each other) which will cause differences in solvency. A highly paraffinic solvent will have less solvency and so be less likely to remove paint or attack plastics, but will still swell rubber & lift most oils etc. Highly aromatic formulations have better solvency but are more harmful both to you & to plastics etc.

The elements I'm currently working on are proving difficult to get totally clear even using aggressive solvents like acetone, but they are gradually improving - you could barely see through them when I started, now after two tries they've almost reached the point where I wouldn't have felt the need to strip them from the lens i.e. almost good enough that I could make do, certainly not good enough to consider done.


PostPosted: Wed May 22, 2019 9:01 am    Post subject: Reply with quote

Perhaps the best way to avoid or minimize scrubbing of highly contaminated surface is the same as with anything else: give it a proper soak.
By proper, I mean several days of it.

I wouldn't do this to a group though.
Whether it looks glued or not, there is a chance of getting solvent inside, and that would create a bigger problem than the initial haze was.


PostPosted: Wed May 22, 2019 9:23 am    Post subject: Reply with quote

I use the naphtha that's available at the big box stores -- dunno specifically what it is, although I guess the fine print on the can will tell me. I've used it for years, however, without harmful effects. I also use naphtha when finishing guitars. I use a method known as "french polish" where naphtha is lightly mixed with the shellac as a means of extending it before it becomes tacky. But that's a whole different world from cameras.

As for iso-proponal, I wish I could find 100%, the best I've been able to find is 70%. I find that denatured alcohol is a more powerful solvent anyway, but I suspect that one should use it with caution because I know it can damage finishes, so it might also be a bit too agressive with some plastics. But it is a great solvent, and is also a main ingredient in the "french polish" process, which is why I always keep some around.


PostPosted: Wed May 22, 2019 10:54 am    Post subject: Reply with quote

Amazon has everything.


PostPosted: Thu Nov 17, 2022 3:52 pm    Post subject: Reply with quote

Hi everyone, I'm trying to clean a yashica ML 50mm 1.4 optic full of fungus , but this lens has been glued on every part possible . I've got rid of the front name plate ring , and the ring to remove elements on front group, but i stil need to remove the mount ring that has the 4 screws ,with acetone I've had luck with everything that I've opened till now, but not further more. Any advice ?


PostPosted: Fri Nov 18, 2022 10:46 am    Post subject: Reply with quote

kiddo wrote:
Hi everyone, I'm trying to clean a yashica ML 50mm 1.4 optic full of fungus , but this lens has been glued on every part possible . I've got rid of the front name plate ring , and the ring to remove elements on front group, but i stil need to remove the mount ring that has the 4 screws ,with acetone I've had luck with everything that I've opened till now, but not further more. Any advice ?


I sometimes encounter mount screws that are simply stuck, no matter what.

First, from the images of that lens I have seen on-line, it looks like (as expected really) the mount screws have JIS (Japanese Industrial Standard) heads. They don't have the JIS indicator dot(s), but the shape of the crosshead looks like a JIS crosshead to me. On stuck JIS screws you really don't want to be using a Philips screwdriver, use an appropriate JIS screw driver.

You say the lens is full of fungus, which indicates a period of storage at high humidity levels. I'm not 100% sure what materials are involved here (likely steel screws in an aluminium alloy base), but it is possible to get corrosion building up in the threads between the screw and lens base, which may not necessarily be evident from the exterior appearance. If so, no amount of acetone is going to help, but a small amount of a penetrating oil (like WD-40) that breaks down the oxide layer may (I stress may) do the trick. I would normally advise to keep agents like WD-40 far away from any lens, but on stuck screws it may be of use. Just place a tiny amount in the round recess for the screw head only and let it penetrate into the thread for a a few hours.

A heated screwdriver applied to the screw head also sometimes works, but it is rarely enough to break an oxide bond or soften a thread-lock compound.

Sometimes a well-fitting screwdriver inserted in the screw sharply hit with a light hammer can break it loose, but be careful not to damage anything.

Bear in mind that on old lenses, sometimes things simply have got stuck beyond the ability to get them undone without excessive damage to other parts. It happens.


PostPosted: Fri Nov 18, 2022 11:50 am    Post subject: Reply with quote

RokkorDoctor wrote:
kiddo wrote:
Hi everyone, I'm trying to clean a yashica ML 50mm 1.4 optic full of fungus , but this lens has been glued on every part possible . I've got rid of the front name plate ring , and the ring to remove elements on front group, but i stil need to remove the mount ring that has the 4 screws ,with acetone I've had luck with everything that I've opened till now, but not further more. Any advice ?


I sometimes encounter mount screws that are simply stuck, no matter what.

First, from the images of that lens I have seen on-line, it looks like (as expected really) the mount screws have JIS (Japanese Industrial Standard) heads. They don't have the JIS indicator dot(s), but the shape of the crosshead looks like a JIS crosshead to me. On stuck JIS screws you really don't want to be using a Philips screwdriver, use an appropriate JIS screw driver.

You say the lens is full of fungus, which indicates a period of storage at high humidity levels. I'm not 100% sure what materials are involved here (likely steel screws in an aluminium alloy base), but it is possible to get corrosion building up in the threads between the screw and lens base, which may not necessarily be evident from the exterior appearance. If so, no amount of acetone is going to help, but a small amount of a penetrating oil (like WD-40) that breaks down the oxide layer may (I stress may) do the trick. I would normally advise to keep agents like WD-40 far away from any lens, but on stuck screws it may be of use. Just place a tiny amount in the round recess for the screw head only and let it penetrate into the thread for a a few hours.

A heated screwdriver applied to the screw head also sometimes works, but it is rarely enough to break an oxide bond or soften a thread-lock compound.

Sometimes a well-fitting screwdriver inserted in the screw sharply hit with a light hammer can break it loose, but be careful not to damage anything.

Bear in mind that on old lenses, sometimes things simply have got stuck beyond the ability to get them undone without excessive damage to other parts. It happens.


Thank you so much for your answer .
The fungus has cleaned away pretty nice, a bit of the edges coatings affected left over on the front group I could remove till now.
The screws are JIS and I'm using specific screwdriver , the screws are mare of steel just as the mount, but I assume they are screwed into aluminum. The front group has a ring to use with a spanner to open it , but that one is glued also , after two days of acetone applying ,no results at all. Otherwise the lens is brand new , I can see the focusing ring's screws inside the lens (3 of them steel made) all have a red glue on top of them and surrounding. Just as the retaining front ring for the front grip , that I was able to open with acetone ,I assume most of the threaded parts have the same glue so no corrosion suspicious at all. I've read about using CRC brake cleaner (the red one) to unlock red glue on threads , or using a very fine torch to heat up properly to get em loosen. I assume repair shops would have a better option but i don't know any other one and I feel bad because of this lens, that is supposed to fill the gap on my c/ymissing FL


PostPosted: Fri Nov 18, 2022 3:39 pm    Post subject: Reply with quote

When I suspect corrosion, I usually turn to the heavy duty stuff -- automotive penetrant like Liquid Wrench or Sea Foam Deep Creep or other similar products. I've also had good luck with glued items using Goof Off's Pro Strength Remover, which is intended for removing adhesives and glues and even dried paint. It smells like acetone, but there are probably additives. And, as RokkorDoctor mentioned with WD-40, it should be applied very sparingly. Perhaps with a blunted toothpick so it can be precisely applied.


PostPosted: Fri Nov 18, 2022 11:26 pm    Post subject: Reply with quote

cooltouch wrote:
When I suspect corrosion, I usually turn to the heavy duty stuff -- automotive penetrant like Liquid Wrench or Sea Foam Deep Creep or other similar products. I've also had good luck with glued items using Goof Off's Pro Strength Remover, which is intended for removing adhesives and glues and even dried paint. It smells like acetone, but there are probably additives. And, as RokkorDoctor mentioned with WD-40, it should be applied very sparingly. Perhaps with a blunted toothpick so it can be precisely applied.


Thanks for your reply, but I can't find the products you recommend in Europe . As for acetone applying ,I'm using a small syringe to allow only the right amount on top of the screws , but no luck after two days .


PostPosted: Fri Nov 18, 2022 11:34 pm    Post subject: Reply with quote

kiddo wrote:
cooltouch wrote:
When I suspect corrosion, I usually turn to the heavy duty stuff -- automotive penetrant like Liquid Wrench or Sea Foam Deep Creep or other similar products. I've also had good luck with glued items using Goof Off's Pro Strength Remover, which is intended for removing adhesives and glues and even dried paint. It smells like acetone, but there are probably additives. And, as RokkorDoctor mentioned with WD-40, it should be applied very sparingly. Perhaps with a blunted toothpick so it can be precisely applied.


Thanks for your reply, but I can't find the products you recommend in Europe . As for acetone applying ,I'm using a small syringe to allow only the right amount on top of the screws , but no luck after two days .


Neat Wintergreen oil is a key ingredient in some penetrating oils. Local pharmacy should have small quantity for little money. Plus it smells nice.


PostPosted: Sat Nov 19, 2022 7:35 am    Post subject: Reply with quote

I still suspect that the issue is the glue they've used at that time , so ,need to figure out how to deal with it. Heat or cold applying ,what should be working better ?


PostPosted: Sat Nov 19, 2022 8:29 pm    Post subject: Reply with quote

I'm thinking heat, but if it's something tiny like a camera or lens screw, you might try applying it with a soldering gun with a pointy tip. One of the modern ones with adjustable temperature might be advisable as well.


PostPosted: Sat Nov 19, 2022 9:36 pm    Post subject: Reply with quote

cooltouch wrote:
I'm thinking heat, but if it's something tiny like a camera or lens screw, you might try applying it with a soldering gun with a pointy tip. One of the modern ones with adjustable temperature might be advisable as well.


Modern ones I've seen a gas torch soldering tool that's got a tip like a thin tube to attach , but not available around here , even though might be interesting. I've seen a YouTube video where a guy is trying different techniques on glued threads and seems like a soldering tip ain't enough to heat up properly . Other guy's mentioning like red CRC brake pads cleaner , I'm sure some others might have different techniques.


PostPosted: Sat Nov 19, 2022 10:18 pm    Post subject: Reply with quote

kiddo wrote:
cooltouch wrote:
I'm thinking heat, but if it's something tiny like a camera or lens screw, you might try applying it with a soldering gun with a pointy tip. One of the modern ones with adjustable temperature might be advisable as well.


Modern ones I've seen a gas torch soldering tool that's got a tip like a thin tube to attach , but not available around here , even though might be interesting. I've seen a YouTube video where a guy is trying different techniques on glued threads and seems like a soldering tip ain't enough to heat up properly . Other guy's mentioning like red CRC brake pads cleaner , I'm sure some others might have different techniques.


If it is truly red locktite use a soldering iron of adequate power -- at least 200 Watts -- to heat the screw & melt the locktite without heating the surrounding mount too much.


PostPosted: Sun Nov 20, 2022 9:16 am    Post subject: Reply with quote

Truth is my soldering tool's got only 30watt so possible a 200w or higher might do the job


PostPosted: Sun Nov 20, 2022 12:07 pm    Post subject: Reply with quote

cooltouch wrote:
I'm thinking heat, but if it's something tiny like a camera or lens screw, you might try applying it with a soldering gun with a pointy tip. One of the modern ones with adjustable temperature might be advisable as well.


I have tried this as well myself, but in practice I find the difficulty is that the screws tend to be screwed into a fairly chunky aluminium component, which is and excellent heat sink.

The thermal contact between the tip of a soldering iron and the screw head is poor, so unless someone has some welcome tips on how to do this well, I have found that even with a 100W soldering iron the aluminium component holding the screw pulls the heat out of the screw faster than the soldering iron can transfer it in, even with the use of a small drop of solder to improve heat transfer (traditional Pb/Sn solder for electronics that won't wet on either steel on aluminium; you don't want to end up soldering the screw in place).

The results I have obtained is a hot screw head, with an at best warm screw body sitting in a cool aluminium heat-sink thread; not enough to melt the thread-lock (and not to mention the damage done to the coating of the soldering tip.)

Heating the whole lot with a small blow-torch would probably do it, and I have had success with that on some older all-metal lenses, but that is usually not an option (for me) as there are often plastic parts and/or cemented lenses nearby (especially near stuck thread-locked zoom cams... Sad )